1. Field of the Invention
The present invention relates to the field of liquid crystal display, and in particular to an anti-leak backlight module.
2. The Related Arts
Liquid crystal display (LCD) has a variety of advantages, such as thin device body, low power consumption, and being free of radiation, and is thus widely used. Most of the LCDs that are currently available in the market are backlighting LCDs, which comprise a liquid crystal panel and a backlight module. The operation principle of the liquid crystal panel is that liquid crystal molecules are interposed between two parallel glass substrates and a plurality of vertical and horizontal fine electrical wires is arranged between the two glass substrates, whereby the liquid crystal molecules are controlled to change direction by application of electricity in order to refract out light emitting from the backlight module for generating images. Since the liquid crystal panel itself does not emit light, light must be provided by the backlight module in order to normally display images. Thus, the backlight module is one of the key components of an LCD. The backlight module can be classified in two types, namely side-edge backlight module and direct backlight module, according to the position where light gets incident. The direct backlight module comprises a light source, such as a cold cathode fluorescent lamp (CCFL) or a light-emitting diode (LED), which is arranged at the back side of the liquid crystal panel to form a planar light source that directly provides lighting to the liquid crystal panel. The side-edge backlight module comprises a backlighting source of an LED light bar arranged at an edge of a backplane that is located rearward of one side of the liquid crystal panel. The LED light bar emits light that enters a light guide plate (LGP) through a light incident face of the light guide plate and is projected out through a light emergence face of the light guide plate to thereby transmit through an optic film assembly, after being reflected and diffused, to form a planar light source for the liquid crystal panel.
Referring to FIG. 1, with the development of using an LED light bar 100 as a backlighting source, a thin-frame backlight module becomes the trend of the future development. To cope with the thin-frame designs and at the same time to ensure the reliability of an optic film assembly 200, since the width of the optic film assembly 200 that is held down by a mold frame 300 is very small, to prevent the optic film assembly 200 from sliding off the backlight module, the general arrangement is to have the optic film assembly 200 straight extending to the very edge of a light guide plate 400. This arrangement allows the light from the LED light bar 100 to project through gaps between the mold frame 300 and the light guide plate 400 and those between the mold frame 300 and a backplane 500, thereby leading to light leak.
Referring to FIG. 2, to obviate the shortcoming, a currently adopted solution is to attach a white reflection plate 600 on the mold frame 300 at a location corresponding to the light incidence side so as to reflect back light that travels to the gaps between the mold frame 300 and the light guide plate 400 and those between the mold frame 300 and the backplane 500 in order to make the light get into the light guide plate 400 as much as possible to improve luminous efficacy. However, in practice, due to gaps existing between the mold frame 300 and the light guide plate 400 and the LED light, the white reflection plate 600 that is attached to the mold frame 300 cannot completely reflect all the light back into the light guide plate 400. The cooperative effect of the reflection plate 600 and the gaps causes the light from the LED light to travel along light paths that are respectively indicated by circled 1 and circled 2 in the drawings to project out of an upper surface of the light guide plate 400 and an upper surface of the LED light, resulting in light leak.